The present invention relates to a side airbag apparatus that deploys and inflates an airbag beside an occupant seated in a vehicle seat to reduce an impact applied from the side, thereby protecting the occupant.
Apparatuses for protecting an occupant from an impact applied from the side of a vehicle, for example, due to a side collision have been known as disclosed in Japanese Laid-Open Patent Publication No. 2007-331401 and Japanese Laid-Open Patent. Publication No. 11-91486. These publications disclose side airbag apparatuses that deploy and inflate an airbag toward a side of an occupant from the backrest of a vehicle seat.
Such a side airbag apparatus includes an airbag module, which is formed by an inflation fluid generator that ejects inflation fluid and an airbag that accommodates the inflation fluid generator and is folded toward the inflation fluid generator. The airbag module is accommodated in the backrest of a seat.
According to the above described side airbag apparatus, when a sensor detects that an impact from the side of the vehicle (seat) is applied, the inflation fluid generator ejects inflation fluid, so that the pressure of the inflation fluid deploys and inflates the airbag. The airbag pops out from the backrest to enter the gap between the occupant seated in the seat and the wall of the passenger compartment. The airbag, which has been deployed and inflated, is located between the passenger compartment side wall and the occupant, restrains the occupant, and reduces and absorbs the impact transmitted to the occupant. Accordingly, the occupant is protected from impact.
In such a side airbag apparatus, it is preferable that the rear portion of the airbag, which is relatively closer to the backrest, be inflated early to quickly restrain and protect an occupant and that deployment of the front portion of the airbag be performed prior to its inflation so that the airbag quickly enters the gap between the occupant and the wall of the passenger compartment. In this respect, Japanese Laid-Open Patent Publications No. 2007-331401 and No. 11-91488 each disclose a side airbag apparatus in which the rear portion of an airbag is folded by according-folding, in which the direction of folding is alternately changed, and the front portion is folded by roll-folding, in which the airbag is folded repeatedly in one direction.
However, in the side airbag apparatuses disclosed in Japanese Laid-Open Patent Publications No. 2007-331401 and No. 11-91488, since an inflation fluid supply source supplies inflation fluid to an airbag, which is formed by a single chamber, the rear portion and the front portion of the airbag are both deployed and inflated at an early stage. Thus, if there is an obstacle in front of the airbag, the rear portion and the front portion may be prevented from being properly deployed and inflated. The rear portion of the airbag therefore may fail to quickly restrain and protect an occupant.